I have a working Chrome extension using manifest version 3, and I am following the porting instructions to turn it into a Safari extension on MacOS (Monterey) - using xcrun from the Xcode toolset. I have Safari v. 15.5. There are two problems. First, the documentation says "Safari 15.4 and later supports manifest versions 2 and 3". So how come xcrun complains about all of the following keys: manifest_version, icons, description, version, js, matches, service_worker, type, action, tabs, activeTab, storage, alarms, webNavigation, web_accessible_resources, name, css? At least some of those are basic to v3 manifests. Second, when I try to install it in Safari (it builds OK under Xcode despite the above "problem") I get an error. In my background (service worker) script I call self.importScripts("Platform.js"); which should load said JavaScript file. It's in the same folder as the script that calls it. This works in Chrome but fails in Safari with the error: Failed to load resource: unsupported URL safari-web-extension://FE580C4D-9931-4639-ABF9-...../Platform.js I tried changing that dynamic import to a static import: import Platform from "./Platform.mjs"; (After converting Platform.js to a module Platform.mjs.) This also works on chrome but now my converted extension for Safari won't even load. I get: The service_worker script failed to load due to an error. But I can find no way of determining what that error is (there is no information in the service worker console). I would appreciate help with either or both of these problems. Perhaps they are connected and there is something missing/wrong about my version 3 manifest - even though Chrome is happy with it.